How to add a custom field to the Edit Order page

Question

I've been googling and searching here for a simple way to add an empty field box to the Edit Orders page. We will use this to put in a reference for the shipment from our courier.

We would add it to the order notes, but we want it to be searchable, and also want to add it as a column in the Orders Admin page (I have Admin Columns plugin that I think can do that bit, I just need to add this field to start).

Hope someone can help, thanks!

EDIT:

I found this question which seems to be similar, but more complicated, than what I am looking for and I cant figure out how to simplify it. Add a custom meta box on order edit pages and display it on the customer order pages

I don't need anything that will display on the front end to customers like this. Just a simple empty box that displays on every order-edit page (perhaps below the order notes) that can be searched. I will then display it in a column on the order admin page too.

Answer 1

Managed to get an answer, this is working great!

//from::https://codex.wordpress.org/Plugin_API/Action_Reference/manage_posts_custom_column

// For displaying in columns.

add_filter( 'manage_edit-shop_order_columns', 'set_custom_edit_shop_order_columns' );
function set_custom_edit_shop_order_columns($columns) {
    $columns['custom_column'] = __( 'Custom Column', 'your_text_domain' );
    return $columns;
}

// Add the data to the custom columns for the order post type:
add_action( 'manage_shop_order_posts_custom_column' , 'custom_shop_order_column', 10, 2 );
function custom_shop_order_column( $column, $post_id ) {
    switch ( $column ) {

        case 'custom_column' :
            echo esc_html( get_post_meta( $post_id, 'custom_column', true ) );
            break;

    }
}

// For display and saving in order details page.
add_action( 'add_meta_boxes', 'add_shop_order_meta_box' );
function add_shop_order_meta_box() {

    add_meta_box(
        'custom_column',
        __( 'Custom Column', 'your_text_domain' ),
        'shop_order_display_callback',
        'shop_order'
    );

}

// For displaying.
function shop_order_display_callback( $post ) {

    $value = get_post_meta( $post->ID, 'custom_column', true );

    echo '<textarea style="width:100%" id="custom_column" name="custom_column">' . esc_attr( $value ) . '</textarea>';
}

// For saving.
function save_shop_order_meta_box_data( $post_id ) {

    // If this is an autosave, our form has not been submitted, so we don't want to do anything.
    if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
        return;
    }

    // Check the user's permissions.
    if ( isset( $_POST['post_type'] ) && 'shop_order' == $_POST['post_type'] ) {
        if ( ! current_user_can( 'edit_shop_order', $post_id ) ) {
            return;
        }
    }

    // Make sure that it is set.
    if ( ! isset( $_POST['custom_column'] ) ) {
        return;
    }

    // Sanitize user input.
    $my_data = sanitize_text_field( $_POST['custom_column'] );

    // Update the meta field in the database.
    update_post_meta( $post_id, 'custom_column', $my_data );
}

add_action( 'save_post', 'save_shop_order_meta_box_data' );

Answer 2

Use the default WooCommerce custom field in the order edit page bottom section.